'Runner's Trots' are a real thing, and they're not fun

Diniz, apparently with a sponge in his shorts to try and soak up the problems. NBC

According to the Mayo Clinic, scientists still aren't sure exactly what causes runner's diarrhea, but they have some compelling theories. Some suggest it's a result of the severe physical jostling a marathon can impose on your internal organs. Others think it happens after prolonged periods of decreased blood flow to your intestines.

Personally, the one that hits home the most for me is pre-race anxiety and stress. As a former competitive swimmer, I can honestly say there's no sensation that quite equals the stomach-churning fight-or-flight butterflies I used to get just before diving into the water.

Aside from diarrhea, many long-distance runners and race-walkers experience other health issues during or after training, including acid reflux, a condition with effects like heartburn, indigestion, coughing, hoarseness, and asthma.

There's even some evidence to suggest that prolonged, intense exercise — like the kind you'd do in the weeks and months before a marathon and during the race — can negatively affect your immune system by reducing the body's natural ability to fend off upper-respiratory infections including colds and the flu.

Marathoners, meet interval training

Still, there's good news for those of us who are committed to working out. There's plenty of evidence, in fact, that suggests you can get some of the same benefits of long-distance running and other types of endurance training without ever passing the five-mile mark.

That's right. Running fast and hard for just five to 10 minutes a day may help add years to your life, just as running for hours can. In fact, people who run for less than an hour a week — so long as they get in their few minutes of daily running — appear to rack up similar benefits in terms of heart health compared with people who run more than three hours a week.

One of the most popular forms of the quick workout — and the one that has been studied the most — is interval training. Basically, you work yourself as hard and fast as you can for a few minutes, rest, then do it again. The best part? It typically lasts only between five and 10 minutes total. (There's even an app based on the idea, called the 7-Minute Workout, which you can read more about here.)

So, whether you stick to a long-distance routine or opt for a quicker, daily exercise plan, it's important to keep in mind that more is not always better.